The present invention relates to automatic washers and in particular to a trap for foreign objects in a washer.
In automatic clothes washers it is preferred that only fabric materials be placed into the wash zone of the wash tub, however, other objects make their way into the wash zone including buttons, keys, stones and pebbles, small metal objects, etc. which can cause damage to the pumps used in the automatic washers such as the recirculation pump and the drain pump.
In some washers it is desirable to use motors such as synchronous motors to drive the recirculation pumps. These types of motors have relatively low efficiency and low torque, but also low cost. Flow rates through these recirculation pumps are maximized by maintaining a close relationship between the impeller and the pump housing. These factors make this type of pump very susceptible to problems caused by foreign materials. Foreign materials are easily trapped between the impeller and housing because of the close relationship. Low torque of the driving motor causes the trapped materials to completely stop the pump.
Collecting and holding foreign materials can cause a number of problems. Collective materials can eventually reduce flow rates by obstructing water flow path. Some collected materials deteriorate with time and may be redistributed on clothing or cause odor. Other types of materials may add to the accumulation process by causing materials to accumulate that might otherwise be pumped down the drain.
A foreign objects trap is disclosed in U.S. Pat. No. 4,485,645 in which a container is provided which has a water inlet in communication with a tub outlet. The water inlet terminates just short of a floor of the container and the water is then required to pass up through a plate which has irregularly shaped tubes therethrough for preventing passage of foreign objects. Lint is specifically permitted to pass through the foreign objects trap and all of the water exits from the container through a single outlet leading to a single pump which is utilized to both recirculate water and drain water, depending upon the position of a valve located downstream of the pump. Thus, this foreign objects trap has a disadvantage of allowing lint to be recirculated onto the clothes load and also accommodates only a single pump.
U.S. Pat. No. 4,833,900 discloses a foreign objects filter for an automatic water through which all of the water from the wash tub is directed. In an embodiment, one part of the filter comprises a fine mesh filter and the outlet of that portion leads to the recirculation pump. The other side of the filter has a coarse mesh and its outlet leads to the drain pump. In a second embodiment, only a coarse filter is provided whose outlet leads to either the recirculation pump and the drain pump. This device permits the passage of small, but heavy objects, such as nails and screws to the drain pump, potentially causing damage to that pump.
The present invention provides a system that allows a drain pump to pass as much foreign material down the drain as possible, other than very dense objects yet prevents a large portion of the foreign material from entering the recirculation pump.
The present invention, in an embodiment, provides a container separated from, but connected to the tub, perhaps with a hose. Both the drain and the recirculation pumps are commonly mounted to this container. The container is designed to allow some foreign objects, such as toothpicks and lint, to pass through to the drain pump which is capable of handling normal quantities of these materials without a problem due to its higher torque motor and larger clearances within the pump. The container is designed to prevent heavier and denser foreign objects such as screws, nails, curtain hooks, metal chains, etc. from reaching either the drain or recirculation pump. The container also incorporates a filter mechanism designed to prevent certain amounts of lint and other light objects from entering the recirculation pump. This is important for two reasons. First, it is not desirable to allow lint to be recirculated over clothes and second, a low cost recirculation pump can handle only small quantities of lint, as explained above. The filter mechanism is also designed and oriented to allow lint collected during the operation of the recirculation pump to be removed from the filter mechanism when the drain pump is operated, thus automatically cleaning the filter.
In an embodiment of the invention, a platform is provided directly below, in close proximity with, and extending completely beyond the wash liquid inlet from the hose which is connected to the tub. The wash liquid may be comprised mainly of water, with detergents and other additives, or may be a non-aqueous liquid. The term xe2x80x9cwaterxe2x80x9d as used herein is meant to include all wash liquids, whether or not they actually contain water. The close proximity of the platform, as well as its orientation of being substantially perpendicular to the water flow through the inlet, causes heavier foreign objects to impact the platform as they are moved along with the water. This makes them lose some of their kinetic energy. The platform then drops down creating an area that is relatively stagnate in which the heavy foreign materials fall and are held. It is likely that some heavy foreign materials can be carried along with the water in spite of hitting the platform. A baffle is provided causing further obstruction to heavy objects that may not have been trapped. The baffle extends upwardly from the floor of the trap with an opening near the top dimension to allow water to easily flow. A second baffle may be provided further downstream for the same purpose. The top of each baffle preferably is higher than the platform, so energy loss from hitting the platform will likely not allow a heavy foreign object to reach the top of the container. Designed as described, most heavy foreign objects will be trapped, while lighter foreign objects easily pass over the baffles to the drain and are disposed down the drain pipe.
During operation of the recirculation pump, heavy foreign objects are easily trapped because of the reduced flow rate. Lighter objects such as lint can still move with the water flow to the pump, so it should be protected from these materials. An obstruction wall is provided in front of the inlet to the recirculation pump. This wall has two purposes. The wall prevents the trapped heavy foreign objects from entering the recirculation pump inlet and it provides obstruction to reverse flow through the recirculation pump when the drain pump is operating. Reverse flow through the recirculation pump can cause air to be pulled into the system. This reduces drain flow and can cause unwanted noise. Another smaller wall is provided between the drain pump inlet and the recirculation obstruction wall. Since it is desired that lighter foreign objects be allowed to travel to the drain pump inlet chamber, they must be prevented from entering the recirculation from this chamber making the smaller wall necessary. The only water flow path to the recirculation pump is therefore over the top of the baffle walls. It is possible for large amounts of lint and toothpicks to pass over the baffle walls and enter the recirculation pump, so a series of fins in the lid of the trap are incorporated as the smaller wall and act as a filter mechanism. When the lid is assembled, these fins make contact along the top and sides of the walls. The fins are specifically designed with dimensions that prevent toothpicks from getting into the recirculation pump. The dimensions further allow certain amounts of lint to pass to the recirculation pump while larger amounts tend to wrap around the fins. This reduces openings to the recirculation pump causing more lint to be collected by the filter, thus preventing lint from being recirculated while protecting the pump from obstruction. The fins are oriented in shape so that the lint is automatically pulled off of the fins when the drain pump is activated, thus providing a self cleaning of the filter.
The lid might also be designed to integrate an air dome with pressure sensors directly mounted above the air dome. Since the trap/filter is hydraulically connected to the tub, the sensors can be used to determine water levels or a possible flood condition. Integrating these devices further reduces cost for this function.
A further advantage of utilizing a remote sump is to provide heat to the water flowing through the sump. The use of a heater to raise water temperature in an automatic washer is not new. It is normally accomplished by providing the tub with a sump and then mounting a calrod heater in the sump area. It has become desirable to reduce water usage in machines and as water levels are reduced, heating water becomes more important. Tap water from the inlet may be heated as it enters the machine, but it loses much of its thermal energy due to a cold basket, tub and clothes.
One of the methods of washing clothes which is employed to reduce water consumption and/or improve performance without additional water, is the xe2x80x9ccatalystxe2x80x9d portion of a wash cycle. The xe2x80x9ccatalystxe2x80x9d portion of a cycle usually takes place during the initial fill where small amounts of water are added to provide a more concentrated detergent to help remove stains and soils. The reduced water will not be an amount sufficient to cover the clothes, so it must be recirculated over the clothes with a pump. Since only a small amount of water is used during the initial fill, and due to the fact that the clothes, the basket and the tub will be cold during this period, benefits of any thermal energy during xe2x80x9ccatalystxe2x80x9d becomes almost insignificant. Thermal energy can be re-gained by incorporating a heater into the wash system. A sump heater has a draw back that because of the smaller amounts of water during xe2x80x9ccatalystxe2x80x9d the heater could become uncovered, resulting in the heater sheath becoming extremely hot. It is therefore necessary to add enough water to ensure the heater will be covered, which will dilute the desired detergent concentration, as well as increase in water usage. If the depth of the sump is small, in order to minimize water and increase detergent concentration, the water level in the sump may be in close proximity to the basket. The close proximity of the sump water then causes concern for xe2x80x9csuds lockxe2x80x9d a condition when heavy suds can touch the basket, increasing forces necessary to drive or spin the basket.
The total sump volume of a machine might be considered to be the volume of the tub sump plus the volume of any remote sump. Since part of the water to feed the inlet of the recirculation pump is in the remote sump, the volume of the tub sump can be reduced by a like amount. In fact, the only remaining purpose of the tub sump is to provide an area to hold water that might be needed to cover a heating element if one is used. There are, however, benefits in the eliminating the tub sump altogether in favor of a remote sump with an integral heater. The remote sump can be designed to house a cal-rod heating element and associated temperature sensor. If this is done, the element could be located in the remote sump container such that is it below the inlet to recirculation pump as well as the drain pump. Both pumps would be air locked and stop pumping should the water level be reduced below the highest point of their inlets. With the heater below this point, it essentially becomes impossible that the heater will become uncovered except through evaporation or leakage. It is further possible that a film heater can be molded into or become the bottom of a remote sump allowing it to retain its compact features while still incorporating the heater. In addition to these advantages, total water height, and therefore its proximity to the basket during xe2x80x9ccatalystxe2x80x9d, can be lower within the system, reducing or eliminating the possibility of suds lock.
A film heater may be described as a substrate on which a resistive element is printed by silk screen or other similar process into a desired pattern. These devices are widely available and may include temperature sensors also printed as a part of the device. The substrate may be made of a flexible high temperature plastic or ceramic. Substrates may also be stainless steel with a layer of insulation material printed on the steel before the resistive material is printed. The substrate material may also be metal with a porcelain layer covering the metal to which the resistive layer is printed.